adjust the extent of brake pedal free play

boost the force applied to brake pedal

convert brake pedal force into hydraulic pressure

ensure that all the wheel brakes are supplied with the same amount of fluid pressure

enhances safety by serving two independent lines in a divided line brake circuit

enhances safety by activating the brakes using vacuum pressure in the event of brake fluid loss

supplies equal fluid pressure to each line of a divided line brake circuit, thereby preventing the brakes from dragging on one side

boosts the brake fluid pressure to reduce the force required to depress the brake pedal

exhaust manifold pressure

electricity

the pressure difference between the atmospheric pressure and the vacuum pressure in the intake manifold

hydraulic pump

mechanically

hydraulically

pneumatically

none of these

front wheels

rear wheels

front and rear wheels

propeller shaft